Mercurial > hg > Members > kono > nitros9-code
changeset 3166:2a29a35c5d2c
L2 kernel: White-space and comment changes (no code changes)
The easy set of changes provoked by mc09 level 2 port.
| author | Neal Crook <foofoobedoo@gmail.com> |
|---|---|
| date | Thu, 06 Apr 2017 23:02:20 +0100 |
| parents | 2d22d31bc74b |
| children | 33f8afc79af2 |
| files | level2/modules/kernel/krn.asm |
| diffstat | 1 files changed, 149 insertions(+), 86 deletions(-) [+] |
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--- a/level2/modules/kernel/krn.asm Thu Apr 06 22:51:54 2017 +0100 +++ b/level2/modules/kernel/krn.asm Thu Apr 06 23:02:20 2017 +0100 @@ -66,7 +66,10 @@ fdb $0055 D.ErrRst ??? Not used as far as I can tell fdb Sys.Vec+Where Initial Kernel system call vector DisSize equ *-DisTable -* DO NOT ADD ANYTHING BETWEEN THESE 2 TABLES: see code using 'SubSiz', below +* ^ +* Code using 'SubSiz', below, assumes that SubStrt follows on directly after +* the end of DisTable. Therefore, DO NOT ADD ADD ANYTHING BETWEEN THESE 2 LABELS +* v LowSub equ $0160 start of low memory subroutines SubStrt equ * * D.Flip0 - switch to system task 0 @@ -77,7 +80,7 @@ ste >DAT.Task and we can use A here, instead of E ELSE pshs a - lda <D.TINIT + lda <D.TINIT Get value from shadow anda #$FE force TR=0 sta <D.TINIT sta >DAT.Task @@ -88,41 +91,62 @@ tfr a,cc rts SubSiz equ *-SubStrt -* Don't add any code here: See L0065, below. +* ^ +* Code around L0065, below, assumes that Vectors follows on directly after +* the end of R.Flip0. Therefore, DO NOT ADD ADD ANYTHING BETWEEN THESE 2 LABELS +* v * Interrupt service routine Vectors jmp [<-(D.SWI3-D.XSWI3),x] (-$10) (Jmp to 2ndary vector) -* Let's start by initializing system page +* Initialize the system block (the lowest 8Kbytes of memory) +* rel.asm has cleared the DP already, so start at address $100. entry equ * - IFNE H6309 + IFNE H6309 ldq #$01001f00 start address to clear & # bytes to clear leay <entry+2,pc point to a 0 tfm y,d+ std <D.CCStk set pointer to top of global memory to $2000 lda #$01 set task user table to $0100 - ELSE - ldx #$100 - ldy #$2000-$100 + ELSE + ldx #$100 start address + ldy #$2000-$100 bytes to clear clra clrb -L001C std ,x++ +L001C std ,x++ clear it 16-bits at a time leay -2,y bne L001C stx <D.CCStk Set pointer to top of global memory to $2000 inca D = $0100 - ENDC + ENDC + +* Set up system variables in DP + std <D.Tasks set Task Structure pointer to $0100 + addb #$20 + std <D.TskIPt set Task image table pointer to $0120 + clrb -* Setup system direct page variables - std <D.Tasks set Task Structure pointer to 0x100 - addb #$20 set Task image table pointer to $0120 - std <D.TskIPt - clrb set memory block map pointer to $0200 +******************************************************************** +* The memory block map is a data structure that is used to manage +* physical memory. Physical memory is assigned in 8Kbyte "blocks". +* 256 bytes are reserved for the map and so the maximum physical +* memory size is 256*8Kbyte=2Mbyte. D.BlkMap is a pointer to the +* start of the map (set to $0200, below). D.BlkMap+2 is a pointer +* to the end of the map. Rather than simply setting it to $0300, +* the end pointer is set by the memory sizing routine at L0111. +* (Presumably) this makes it faster to search for unused pages +* and also acts as the mechanism to avoid assigning non-existent +* memory. A value of 0 indicates an unused block and since the +* system block has been initialised to 0 (above) every block starts +* off marked as unused. Initial reservation of blocks occurs +* below, after the memory sizing. +* See "Level 2 flags" in os9.d for other byte values. + inca std <D.BlkMap addb #$40 set second block map pointer to $0240 std <D.BlkMap+2 - clrb set system service dispatch table - inca pointer to 0x300 + clrb set system service dispatch table pointer + inca to 0x300 std <D.SysDis inca set user dispatch table pointer to $0400 std <D.UsrDis @@ -161,10 +185,9 @@ bne l@ loop if we're not done ENDC -* initialize D.Flip0 routine in low memory, move function down to low -* memory. -* Y=ptr to R.Flip0 already -* leay >R.Flip0,pc +* Initialize D.Flip0 routine in low memory by copying lump of code down from R.Flip0. +* ASSUME: Y left pointing to R.Flip0 by previous copy loop. + ldu #LowSub somewhere in block 0 that's never modified stu <D.Flip0 switch to system task 0 IFNE H6309 @@ -178,8 +201,8 @@ bne Loop2 loop if not done ENDC -* leau <Vectors,pc point to vector -* fill in the secondard interrupt vectors to all point to +* Initialize secondary interrupt vectors to all point to Vectors for now +* ASSUME: Y left pointing to Vectors by previous copy loop tfr y,u move the pointer to a faster register L0065 stu ,x++ Set all IRQ vectors to go to Vectors for now cmpx #D.NMI @@ -206,7 +229,7 @@ leax >S.AltIRQ,pc Setup alternate IRQ vector: pts to an RTS stx <D.AltIRQ - lda #'K --- in Kernel + lda #'K debug: signal that we are in Kernel jsr <D.BtBug --- leax >S.Flip1,pc Setup change to task 1 vector @@ -223,14 +246,14 @@ * These overlap because it is quicker than trying to strip hi byte from X stx ,u save it as first process in table stx 1,u save it as the second as well - IFNE H6309 + IFNE H6309 oim #$01,P$ID,x Set process ID to 1 (inited to 0) oim #SysState,P$State,x Set to system state (inited to 0) - ELSE + ELSE ldd #$01*256+SysState sta P$ID,x set PID to 1 stb P$State,x set state to system (*NOT* zero ) - ENDC + ENDC clra set System task as task #0 sta <D.SysTsk sta P$Task,x @@ -240,15 +263,19 @@ leax <P$DATImg,x point to DAT image stx <D.SysDAT save it as a pointer in DP * actually, since block 0 is tfm'd to be zero, we can skip the next 2 lines - IFNE H6309 + IFNE H6309 clrd - ELSE + ELSE clra clrb - ENDC + ENDC std ,x++ initialize 1st block to 0 (for this DP) -* Dat.BlCt-ROMCount-RAMCount +******************************************************************** +* The DAT image is a data structure that is used to indicate which +* Dynamic Address Translator (DAT) mapping registers are in use. + +* Dat.BlCt-ROMCount-RAMCount = 8 - 1 - 1 = 6 lda #$06 initialize the rest of the blocks to be free ldu #DAT.Free L00EF stu ,x++ store free "flag" @@ -262,17 +289,40 @@ inc ,x mark first 2 in use (system & GrfDrv) inc 1,x -* Setup system memory map +******************************************************************** +* The system memory map is a data structure that is used to manage +* the 64Kbyte CPU address space. D.SysMem is a pointer to the start +* of the map (set to $0900, above) and the map is a fixed size of +* 256 bytes. Each byte in the map represents one 256-byte "page" +* (256 entries of 256 bytes is 64Kbytes). A value of 0 indicates +* an unused page and since the system block has been initialised +* to 0 (above) every page starts off marked as unused. +* See "Level 2 flags" in os9.d for other byte values. + +* Update the system memory map to reserve the area used for +* global memory. ldx <D.SysMem Get system memory map pointer ldb <D.CCStk Get MSB of top of CC memory +* X indexes the system memory map. +* B represents the number of 256-byte pages available. +* Walk through the map changing the corresponding elements +* from 0 (the initialisation value) to 1 (indicating 'used'). Higher +* entries in the map remain as 0 (indicating 'unused'). L0104 inc ,x+ Mark it as used decb Done? bne L0104 No, go back till done -* Calculate memory size +******************************************************************** +* Deduce how many 8Kbyte blocks of physical memory are available and +* update the memory block map end pointer (D.BlkMap+2) accordingly ldx <D.BlkMap get ptr to 8k block map inc <$3F,x mark block $3F as used (kernel) - IFNE H6309 +* This memory sizing routine uses location at X (D.BlkMap) as +* a scratch location. At exit, it leaves this location at 1 which +* has the (until now) undocumented side-effect of marking block 0 +* as used. It is essential that this is done because that block +* does need to be reserved; it's used for global memory. + IFNE H6309 ldq #$00080100 e=Marker, D=Block # to check L0111 asld get next block # stb >DAT.Regs+5 Map block into block 6 of my task @@ -281,7 +331,7 @@ bne L0111 No, keep going till ghost is found stb <D.MemSz Save # 8k mem blocks that exist addr x,d add number of blocks to block map start - ELSE + ELSE ldd #$0008 L0111 aslb rola @@ -295,15 +345,20 @@ stb <D.MemSz pshs x addd ,s++ - ENDC - std <D.BlkMap+2 save block map end pointer + ENDC + std <D.BlkMap+2 save memory block map end pointer -* [D] at this point will contain 1 of the following: -* $0210 - 128k -* $0220 - 256k -* $0240 - 512k -* $0280 - 1024k -* $0300 - 2048k +******************************************************************** +* Initial reservation of blocks in the memory block map. Code above +* reserved one block (block 0) for global memory and one block +* (usually block $3F) for krn. +* +* At this point, the value of D indicates the memory size: +* $0210 - 128k ( 16, 8KByte blocks) +* $0220 - 256k ( 32, 8KByte blocks) +* $0240 - 512k ( 64, 8KByte blocks) +* $0280 - 1024k (128, 8KByte blocks) +* $0300 - 2048k (256, 8KByte blocks) bitb #%00110000 block above 128K-256K? beq L0170 yes, no need to mark block map tstb 2 meg? @@ -317,10 +372,12 @@ decb bne L0127 +* ASSUME: however we got here, B=0 L0170 ldx #Bt.Start start address of the boot track in memory - lda #18 size of the boot track: B=$00 from L0127 loop, above - lbsr I.VBlock go verify it + lda #18 size of the boot track is $1800 +* Verify the modules in the boot track and update/build a module index + lbsr I.VBlock bsr L01D2 go mark system map * See if init module is in memory already @@ -330,16 +387,18 @@ L01B8 os9 F$Boot error linking init, try & load boot file bcc L01B0 got it, try init again bra L01CE error, re-booting do D.Crash -* Save pointer to init module and execute krnp2 + +* So far, so good. Save pointer to init module and execute krnp2 L01BF stu <D.Init Save init module pointer lda Feature1,u Get feature byte #1 from init module bita #CRCOn CRC feature on? beq ShowI if not, continue inc <D.CRC else inc. CRC flag -ShowI lda #'i found init module + +ShowI lda #'i debug: signal that we found the init module jsr <D.BtBug -L01C1 leax <krnp2,pc Point to it's name +L01C1 leax <krnp2,pc Point to its name bsr link Try to link it bcc L01D0 It worked, execute it os9 F$Boot It doesn't exist try re-booting @@ -347,14 +406,14 @@ L01CE jmp <D.Crash obviously can't do it, crash machine L01D0 jmp ,y execute krnp2 -* Mark kernel in system memory map as used memory (256 byte blocks) -L01D2 ldx <D.SysMem Get system mem ptr +* Update the system memory map to reserve the area used by the kernel +L01D2 ldx <D.SysMem Get system memory map pointer ldd #NotRAM*256+(Bt.Start/256) B = MSB of start of the boot abx point to Bt.Start - start of boot track - comb we have $FF-$ED pages to mark as used + comb we have $FF-$ED pages to mark as inUse sta b,x Mark I/O as not RAM -L01DF lda #RAMinUse get in use flag -L01E1 sta ,x+ save it +L01DF lda #RAMinUse get inUse flag +L01E1 sta ,x+ mark this page decb done? bne L01E1 no, keep going ldx <D.BlkMap get pointer to start of block map @@ -581,16 +640,16 @@ ldb 3,u get a second just in case of overlap orcc #IntMasks shutdown interupts while we do this std >DAT.Regs+5 map blocks in - IFNE H6309 + IFNE H6309 ldw #R$Size get size of register stack tfm x+,y+ copy it - ELSE + ELSE ldb #R$Size Loop5 lda ,x+ sta ,y+ decb bne Loop5 - ENDC + ENDC ldx <D.SysDAT remap the blocks we took out lda $0B,x ldb $0D,x @@ -757,13 +816,13 @@ jsr [>D.SvcIRQ] (Normally routine in Clock calling D.Poll) inc <D.SSTskN Save task # for system state lda #1 Task 1 - ora <D.TINIT Merge task bit's into Shadow version + ora <D.TINIT Merge task bit into Shadow version sta <D.TINIT Update shadow - sta >DAT.Task Save to GIME as well & return - bra DoneIRQ Check for error and exit + sta >DAT.Task Save to GIME as well + bra DoneIRQ Check for error and exit FastIRQ jsr [>D.SvcIRQ] (Normally routine in Clock calling D.Poll) -DoneIRQ bcc L0E28 No error on IRQ, exit +DoneIRQ bcc L0E28 No error on IRQ, exit IFNE H6309 oim #IntMasks,0,s Setup RTI to shut interrupts off again ELSE @@ -779,54 +838,54 @@ lbsr TstImg check image, and F$SetTsk (PRESERVES A) orcc #IntMasks Shut interrupts off sta <D.SSTskN Save task # for system state - beq Fst2 If task 0, skip subroutine - ora <D.TINIT Merge task bit's into Shadow version + beq Fst2 If task 0, we're done + ora <D.TINIT Merge task bit into Shadow version sta <D.TINIT Update shadow - sta >DAT.Task Save to GIME as well & return + sta >DAT.Task Save to GIME as well Fst2 leas ,u Stack ptr=U & return rti * Switch to new process, X=Process descriptor pointer, U=Stack pointer L0E4C equ * - IFNE H6309 + IFNE H6309 oim #$01,<D.TINIT switch GIME shadow to user state lda <D.TINIT - ELSE + ELSE lda <D.TINIT ora #$01 sta <D.TINIT - ENDC + ENDC sta >DAT.Task save it to GIME leas ,y point to new stack tstb is the stack at SWISTACK? bne MyRTI no, we're doing a system-state rti - IFNE H6309 + IFNE H6309 ldf #R$Size E=0 from call to L0E8D before ldu #Where+SWIStack point to the stack tfm u+,y+ move the stack from top of memory to user memory - ELSE + ELSE ldb #R$Size ldu #Where+SWIStack point to the stack RtiLoop lda ,u+ sta ,y+ decb bne RtiLoop - ENDC + ENDC MyRTI rti return from IRQ * Execute routine in task 1 pointed to by U * comes from user requested SWI vectors L0E5E equ * - IFNE H6309 + IFNE H6309 oim #$01,<D.TINIT switch GIME shadow to user state ldb <D.TINIT - ELSE + ELSE ldb <D.TINIT orb #$01 stb <D.TINIT - ENDC + ENDC stb >DAT.Task jmp ,u @@ -834,14 +893,14 @@ * by <D.Flip1). All regs are already preserved on stack for the RTI S.Flip1 ldb #2 get Task image entry numberx2 for Grfdrv (task 1) bsr L0E8D copy over the DAT image - IFNE H6309 + IFNE H6309 oim #$01,<D.TINIT lda <D.TINIT get copy of GIME Task side - ELSE + ELSE lda <D.TINIT - ora #$01 + ora #$01 force TR=1 sta <D.TINIT - ENDC + ENDC sta >DAT.Task save it to GIME register inc <D.SSTskN increment system state task number rti return @@ -853,6 +912,10 @@ ldx #DAT.Regs+8 get MMU start register for process's ldu <D.TskIPt get task image pointer table ldu b,u get address of DAT image +* COME HERE FROM FALLTSK +* Update 8 MMU mappings. +* X = address of 1st DAT MMU register to update +* U = address of DAT image to update into MMU L0E93 leau 1,u point to actual MMU block IFNE H6309 lde #4 get # banks/2 for task @@ -870,7 +933,7 @@ ENDC bne L0E9B no, keep going IFEQ H6309 - leas 1,s + leas 1,s done. Tidy up the stack ENDC L0EA3 rts return @@ -879,18 +942,18 @@ bra L0EB8 go execute it * Execute IRQ vector (called from $FEF7) -IRQVCT orcc #IntMasks disasble IRQ's +IRQVCT orcc #IntMasks disable IRQ's ldx #D.IRQ get DP offset of vector * Execute interrupt vector, B=DP Vector offset L0EB8 clra (faster than CLR >$xxxx) sta >DAT.Task Force to Task 0 (system state) IFNE H6309 - tfr 0,dp setup DP + tfr 0,dp setup DP ELSE - tfr a,dp + tfr a,dp ASSUME: A=0 from earlier ENDC -MapGrf equ * +MapGrf equ * come here from elsewhere, too. IFNE H6309 aim #$FE,<D.TINIT switch GIME shadow to system state lda <D.TINIT set GIME again just in case timer is used @@ -899,7 +962,7 @@ anda #$FE sta <D.TINIT ENDC -MapT0 sta >DAT.Task +MapT0 sta >DAT.Task come here from elsewhere, too. jmp [,x] execute it * Execute SWI3 vector (called from $FEEE) @@ -922,11 +985,11 @@ clra sta >DAT.Task * set DP to zero - IFNE H6309 + IFNE H6309 tfr 0,dp - ELSE - tfr a,dp - ENDC + ELSE + tfr a,dp ASSUME: A=0 from earlier + ENDC * These lines add a total of 81 addition cycles to each SWI(2,3) call, * and 36 bytes+12 for R$Size in the constant page at $FExx